The rice FLATTENED SHOOT MERISTEM, encoding CAF-1 p150 subunit, is required for meristem maintenance by regulating the cell-cycle period

摘要

Weisolatedemflattenedshootmeristem/em(emfsm/em)mutantsinricethatshoweddefectiveseedlinggrowthanddiedinthevegetativephase.Sincemostemfsm/emplantshadflatandsmallshootapicalmeristems(SAMs),wesuggestthatemFSM/emisrequiredforproperSAMmaintenance.emFSM/emencodesaputativeorthologofemArabidopsisFASCIATA1/em(emFAS1/em)thatcorrespondstothep150subunitofchromatinassemblyfactor-1(CAF-1).emFSM/emisexpressedpatchilyintissueswithactivelydividingcells,suggestingatightassociationofFSMwithspecificcell-cyclephases.Double-targeteminsitu/emhybridizationcounterstainedwithcell-cyclemarkergenesrevealedthatemFSM/emisexpressedmainlyintheGsub1/subphase.Inemfsm/em,expressionsofthetwomarkergenesrepresentingS-andGsub2/sub-toM-phaseswereenhancedinSAM,despiteareducednumberofcellsinSAM,suggestingthatS-andGsub2/sub-phasesareprolongedinemfsm/em.Inaddition,developmentaleventsinemfsm/emleavestookplaceatthepropertime,indicatingthatthetemporalregulationofdevelopmentoccursindependentlyofthecell-cycleperiod.IncontrasttothefasciatedphenotypeofemArabidopsisfas1/em,emfsm/emshowedsizereductionofSAM.Theoppositephenotypesbetweenemfsm/emandemfas1/emindicatethattheSAMmaintenanceisregulateddifferentlybetweenriceandemArabidopsis/em./p/div